On the completion of the Columbiad the public interest centered
in the projectile itself, the vehicle which was destined to
carry the three hardy adventurers into space.
The new plans had been sent to Breadwill and Co., of Albany,
with the request for their speedy execution.  The projectile was
consequently cast on the 2nd of November, and immediately
forwarded by the Eastern Railway to Stones Hill, which it
reached without accident on the 10th of that month, where Michel
Ardan, Barbicane, and Nicholl were waiting impatiently for it.
The projectile had now to be filled to the depth of three feet
with a bed of water, intended to support a water-tight wooden
disc, which worked easily within the walls of the projectile.
It was upon this kind of raft that the travelers were to take
their place.  This body of water was divided by horizontal
partitions, which the shock of the departure would have to break
in succession.  Then each sheet of the water, from the lowest
to the highest, running off into escape tubes toward the top of
the projectile, constituted a kind of spring; and the wooden
disc, supplied with extremely powerful plugs, could not strike
the lowest plate except after breaking successively the
different partitions.  Undoubtedly the travelers would still
have to encounter a violent recoil after the complete escapement
of the water; but the first shock would be almost entirely
destroyed by this powerful spring.  The upper parts of the walls
were lined with a thick padding of leather, fastened upon springs
of the best steel, behind which the escape tubes were completely
concealed; thus all imaginable precautions had been taken for
averting the first shock; and if they did get crushed, they
must, as Michel Ardan said, be made of very bad materials.
The entrance into this metallic tower was by a narrow aperture
contrived in the wall of the cone.  This was hermetically closed
by a plate of aluminum, fastened internally by powerful
screw-pressure.  The travelers could therefore quit their prison
at pleasure, as soon as they should reach the moon.
Light and view were given by means of four thick lenticular
glass scuttles, two pierced in the circular wall itself, the
third in the bottom, the fourth in the top.  These scuttles then
were protected against the shock of departure by plates let into
solid grooves, which could easily be opened outward by
unscrewing them from the inside.  Reservoirs firmly fixed
contained water and the necessary provisions; and fire
and light were procurable by means of gas, contained in a
special reservoir under a pressure of several atmospheres.
They had only to turn a tap, and for six hours the gas would
light and warm this comfortable vehicle.
There now remained only the question of air; for allowing for
the consumption of air by Barbicane, his two companions, and two
dogs which he proposed taking with him, it was necessary to
renew the air of the projectile.  Now air consists principally
of twenty-one parts of oxygen and seventy-nine of nitrogen.
The lungs absorb the oxygen, which is indispensable for the support
of life, and reject the nitrogen.  The air expired loses nearly
five per cent. of the former and contains nearly an equal volume
of carbonic acid, produced by the combustion of the elements of
the blood.  In an air-tight enclosure, then, after a certain
time, all the oxygen of the air will be replaced by the carbonic
acid-- a gas fatal to life.  There were two things to be done
then-- first, to replace the absorbed oxygen; secondly, to
destroy the expired carbonic acid; both easy enough to do, by
means of chlorate of potassium and caustic potash.  The former
is a salt which appears under the form of white crystals; when
raised to a temperature of 400 degrees it is transformed into
chlorure of potassium, and the oxygen which it contains is
entirely liberated.  Now twenty-eight pounds of chlorate of
potassium produces seven pounds of oxygen, or 2,400 litres-- the
quantity necessary for the travelers during twenty-four hours.
Caustic potash has a great affinity for carbonic acid; and it is
sufficient to shake it in order for it to seize upon the acid
and form bicarbonate of potassium.  By these two means they
would be enabled to restore to the vitiated air its life-
supporting properties.
It is necessary, however, to add that the experiments had
hitherto been made in anima vili.  Whatever its scientific
accuracy was, they were at present ignorant how it would answer
with human beings.  The honor of putting it to the proof was
energetically claimed by J. T. Maston.
"Since I am not to go," said the brave artillerist, "I may at
least live for a week in the projectile."
It would have been hard to refuse him; so they consented to
his wish.  A sufficient quantity of chlorate of potassium and
of caustic potash was placed at his disposal, together with
provisions for eight days.  And having shaken hands with his
friends, on the 12th of November, at six o'clock A.M., after
strictly informing them not to open his prison before the 20th,
at six o'clock P.M., he slid down the projectile, the plate of
which was at once hermetically sealed.  What did he do with
himself during that week?  They could get no information.
The thickness of the walls of the projectile prevented any
sound reaching from the inside to the outside.  On the 20th
of November, at six P.M. exactly, the plate was opened.
The friends of J. T. Maston had been all along in a state of
much anxiety; but they were promptly reassured on hearing a
jolly voice shouting a boisterous hurrah.
Presently afterward the secretary of the Gun Club appeared at
the top of the cone in a triumphant attitude.  He had grown fat!